Category Archives: Nuts

A Mediterranean-style diet with supplemental extra-virgin olive oil seemed to reduce the incidence of breast cancer in a Spanish population. This is consistent with prior observational studies that link the Mediterranean diet with lower rates of breast and other cancers.

The study population involved 4,000 women who were followed for five years. Thirty-five new cases of breast cancer occurred in this PREDIMED study sub-analysis.

The comparison diets were a reduced-fat diet and Mediterranean diet supplemented with mixed nuts.

This is a relatively small study, so results may not be entirely reliable.

Action Plan

If you’re a woman hoping to avoid breast cancer, consider the Mediterranean diet and be sure to eat plenty of extra-virgin olive oil. A good way to do this is to use home-made vinaigrettes.

Steve Parker, M.D.

PS: Even if you think Spaniards are jovial, you won’t find any in my books.

Background Epidemiological studies have consistently associated nut consumption with reduced risk for coronary heart disease. Subsequently, many dietary intervention trials investigated the effects of nut consumption on blood lipid levels. The objectives of this study were to estimate the effects of nut consumption on blood lipid levels and to examine whether different factors modify the effects.

Methods: We pooled individual primary data from 25 nut consumption trials conducted in 7 countries among 583 men and women with normolipidemia and hypercholesterolemia who were not taking lipid-lowering medications. In a pooled analysis, we used mixed linear models to assess the effects of nut consumption and the potential interactions.

Results: With a mean daily consumption of 67 g of nuts [about 2 ounces or 2 palms-ful], the following estimated mean reductions were achieved: total cholesterol concentration (10.9 mg/dL [5.1% change]), low-density lipoprotein cholesterol concentration (LDL-C) (10.2 mg/dL [7.4% change]), ratio of LDL-C to high-density lipoprotein cholesterol concentration (HDL-C) (0.22 [8.3% change]), and ratio of total cholesterol concentration to HDL-C (0.24 [5.6% change]) (P < .001 for all) (to convert all cholesterol concentrations to millimoles per liter, multiply by 0.0259). Triglyceride levels were reduced by 20.6 mg/dL (10.2%) in subjects with blood triglyceride levels of at least 150 mg/dL (P < .05) but not in those with lower levels (to convert triglyceride level to millimoles per liter, multiply by 0.0113). The effects of nut consumption were dose related, and different types of nuts had similar effects on blood lipid levels. The effects of nut consumption were significantly modified by LDL-C, body mass index, and diet type: the lipid-lowering effects of nut consumption were greatest among subjects with high baseline LDL-C and with low body mass index and among those consuming Western diets.

The macadamia nut is that it’s one of the few nuts with a good omega-6/omega-3 fatty acid ratio. In other words, it’s high in omega-3 and low in 6. This may have important cardiovascular health implications. Macadamias are one of the nuts I recommend on my Paleobetic Diet. All of the diets I recommend to my patients include nuts. I just wish macadamias were less expensive.

David writes:

The first Australian macadamia plantation didn’t begin until the 1880s. And not until 1954 with the introduction of mechanised processing did commercial production became viable. Nowadays about 90 percent of the the world’s macadamia nut production comes from Hawaii, where it has become its third most important crop, according to The Wellness Encyclopedia of Food and Nutrition, University of California at Berkeley (1992).

Read the rest, where you’ll learn that macadamia nuts are the highest of all nuts in calories, gram for gram.

Well, perhaps that’s a bit of an overstatement. Preserved brain function and the Mediterranean diet were positively associated in a study involving Americans in Utah. This fits with prior observations that the Mediterranean diet prevents dementia.

In the study at hand, the DASH diet (Dietary Approaches to Stop Hypertension) also protected the brain:

Higher levels of accordance [compliance] with both the DASH and Mediterranean dietary patterns were associated with consistently higher levels of cognitive function in elderly men and women over an 11-year period. Whole grains and nuts and legumes were positively associated with higher cognitive functions and may be core neuroprotective foods common to various healthy plant-centered diets around the globe.

In the largest study of its kind, Harvard scientists found that people who ate a handful of nuts every day were 20% less likely to die from any cause over a 30-year period than those who didn’t consume nuts. The study also found that regular nut-eaters were leaner than those who didn’t eat nuts, a finding that should calm any fears that eating nuts will make you gain weight.

The report also looked at the protective effect on specific causes of death. “The most obvious benefit was a reduction of 29% in deaths from heart disease—the major killer of people in America,” according to Charles S. Fuchs, director of the Gastrointestinal Cancer Treatment Center at Dana-Farber, the senior author of the report and a professor of medicine at Harvard Medical School. “But we also saw a significant reduction—11% —in the risk of dying from cancer,” added Fuchs.

Walnuts seem to have the lowest omega-6/omega-3 fatty acid ratio of all the common nuts. That may make them the healthiest nut. The jury is still out. Paleo dieters focus on cutting out omega-6s and increasing omega-3s. Julianne Taylor has a great post on how to do that with a variety of foods, not just nuts.

In the case of the cashew, someone, somewhere, a long time ago determined that it had to be roasted. The cashew was once nicknamed the blister nut, because if you try to eat it raw from the tree, your mouth pays the price. The cashew is not a nut, however; it’s a seed. On the tree, the fruit that contains it looks like a bloated green kidney bean or a boxing glove dangling comically below an upside-down red or yellow bell pepper, the swollen stalk of the fruit, called the cashew apple.

Just as the cashew isn’t really a nut, this so-called apple is a false fruit. Nonetheless, it’s juicy and edible, but it’s too perishable to ship, lasting only a day off the tree before becoming moldy and starting to rot, which is why it’s not sold in the United States. But in warmer countries…

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Unlike other nuts (false or otherwise), cashews aren’t sold in the shell. That is because the testa skin, the inner lining between the outer shell (the actual fruit) and the kernel (the cashew), is toxic. A relative of poison ivy and poison sumac, the cashew contains the same rash-inducing chemicals, known as urushiols, as its kin. Heating the whole green fruit hardens this toxic stuff, allowing it to be separated from the seed. Once removed, this caustic goo is used in industrial materials such as waterproof paint, varnishes, lacquers, and brake linings, and meanwhile, cashew workers often suffer from skin and eye irritations and minor burns. The processing of cashews is therefore incredibly labor intensive, since most of the many steps—roasting, burning, boiling, soaking, cracking, and peeling—are completed by hand, labor performed by workers in factories primarily in India and Brazil.